1. Field of the Invention
The present invention relates generally to mechanisms for cooling electronic circuit boards, and specifically, to cooling mechanisms that rely on an adapter which couples two circuit boards.
2. Description of the Related Art
Instruments for collecting data or information from an environment or unit under test may be coupled to and controlled by computer systems. Data collected by these instruments may be used to control units being tested (e.g., an overheated unit may be shutdown) or an environment (e.g., ventilation systems may be activated if a certain chemical is detected in the air). Data may also be displayed to a user for control and/or experimental purposes (e.g., to better design the unit being tested). Instruments and/or computer systems may also perform various data analysis and data processing on acquired data prior to controlling the unit and/or displaying the data to the user. Examples of various types of instruments include oscilloscopes, digital multimeters, pressure sensors, etc., and the types of information that might be collected by respective instruments include voltage, resistance, distance, velocity, pressure, frequency of oscillation, humidity or temperature, among others.
Instrumentation systems may run on a platform such as PXI (Peripheral Component Interconnect (PCI) eXtensions for Instrumentation). PXI may combine a high-speed PCI bus with integrated timing and triggering designed for measurement and automation applications to deliver performance improvements over other architectures. PXI may be built on a modular and scalable CompactPCI specification and the high-speed PCI bus architecture. As a result, PXI products may maintain interoperability with CompactPCI, offering increased mechanical integrity, easier systems integration, and more expansion slots than desktop computers. However, due to the compact design of these modules, parts of the module may not be cooled efficiently. Excessive heat can result in shorter component lives and/or unexpected failures.
FIG. 1: Exemplary Chassis
FIG. 1 illustrates an exemplary chassis 100 conforming to any one of the following standards: VXI (Virtual Machine Environment (VME) eXtensions for Instrumentation), VME, CompactPCI, and PXI. The chassis 100 includes a housing that is configured to define a plurality of slots. The housing includes a backplane (not shown) adapted for the transmission of electrical signals. Cards 102A, 102B, and 102C are designed to physically couple to the chassis backplane. Cards 102A, 102B, and 102C may be of either 3 U or 6 U size, as is described below with reference to FIG. 2.
FIG. 2: Various Card Formats
FIG. 2A illustrates different card formats as defined by the IEEE 1101.1, CompactPCI, PXI, and similar specifications. The IEEE 1101.1, CompactPCI, PXI, and similar specifications describe two card sizes, referred to as 3 U and 6 U, and two chassis sizes (also referred to as 3 U and 6 U) designed to accept 3 U and 6 U cards, respectively. The IEEE 1101.1, CompactPCI, PXI, and similar specifications describe the 6 U card size to be more than twice as tall as the 3 U card size.
The increased size and other factors of the 6U card may create cooling problems for various components on the card. Cooling problems may especially be encountered for cards that are coupled together using an adapter. For example, two 3 U cards may be connected by an adapter to form a combined structure as suggested by FIG. 2B. Adapter 250 includes plates 250A and 250B. A region along the upper edge of card 200A and a region along the lower edge of card 200B may be clamped between plates 250A and 250B as the plates are screwed together using coupling elements 240A and 240B. The combined structure may be inserted in a slot of a 6 U chassis.
The ambient air surrounding the combined structure is heated by the electronic components of the combined structure. This heating induces a generally upward flow of the ambient air. Because the upper 3 U card of the combined structure receives air that is already partially heated by the lower 3 U card, electronic components of the upper 3 U card may have more difficulty liberating heat into the ambient air stream and thus are more prone to overheating.
For more information regarding mechanisms for coupling two electronic cards into a combined structure using adapters, please refer to the Description of the Related Art, the Summary, the Detailed Description and the Figures of:                U.S. Pat. No. 6,608,755, entitled “ADAPTER WHICH IS ADAPTED TO RECEIVE CARDS DESIGNED FOR A DIFFERENT FORM FACTOR”, filed on Feb. 27, 2002, invented by Richard Baldwin, Seth Cunningham, and Alvin Becker.        